Surveillance for highly pathogenic H5 avian influenza virus in synanthropic wildlife associated with poultry farms during an acute outbreak

Abstract

In November 2014, a Eurasian strain H5N8 highly pathogenic avian influenza virus was detected in poultry in Canada. Introduced viruses were soon detected in the United States and within six months had spread to 21 states with more than 48 million poultry affected. In an effort to study potential mechanisms of spread of the Eurasian H5 virus, the United States Department of Agriculture coordinated several epidemiologic investigations at poultry farms. As part of those efforts, we sampled synanthropic birds and mammals at five infected and five uninfected poultry farms in northwest Iowa for exposure to avian influenza viruses. Across all farms, we collected 2,627 samples from 648 individual birds and mammals. House mice were the most common mammal species captured while house sparrows, European starlings, rock pigeons, swallows, and American robins were the most commonly captured birds. A single European starling was positive for Eurasian H5 viral RNA and seropositive for antibodies reactive to the Eurasian H5 virus. Two American robins were also seropositive. No mammal species showed evidence of infection. These results indicate synanthropic species merit further scrutiny to better understand potential biosecurity risks. We propose a set of management practices aimed at reducing wildlife incursions.

The role of rodents in avian influenza outbreaks in poultry farms: a review

“…Subsequently, poultry can have direct contact with this rodent induced contamination, or indirectly via movement of poultry workers, equipment or supplies (Shriner et al 2016). However, there is insufficient data to determine the virus load that can be established by this mechanical transmission route, and whether this is likely to result in infection in poultry.…”

“…The number of studies in which rodents were caught in and around AIV infected poultry farms is limited (Nettles et al 1985;Henzler et al 2003;Shriner et al 2012Shriner et al , 2016. In one study, wild house mice tested positive for IAV antibodies (Shriner et al 2012).…”

“…six brown rats (Rattus norvegicus), one harvest mouse (Reithrodontomys megalotis) and one deer mouse (Peromyscus maniculatus). In a study on poultry farms several weeks after HPAIV H5N8 outbreaks in Canada, no evidence of infection in blood samples and respiratory tract tissue of trapped mice was found (Shriner et al 2016). During the HPAIV H5N8 outbreak in the Netherlands in 2014-2015 H5 virus was detected by PCR from the nose of a house mouse that was found dead in a depopulated poultry house, but further typing of the virus failed (Velkers et al 2015).…”

“…Potential vectors contributing to introduction of AIV may be synanthropic animals (i.e. ecologically associated with humans) in the surroundings of poultry farms, such as rodents or wild terrestrial birds (Fujimoto et al 2015;Hiono et al CONTACT Francisca C. Velkers f.c.velkers@uu.nl 2016; Shriner et al 2016) as depicted in Figure 1. Insects, such as houseflies and blowflies, may also be possible vectors in the transmission of HPAIV to chickens (Sawabe et al 2006;Wanaratana et al 2013).…”

“…Poultry can become infected with AIV from wild birds and this could be followed by within-and between-flock spread (Pepin et al 2014). Important factors for primary introduction of AIV from wild birds are contaminated water (Stallknecht & Brown 2009), contact with waterfowl and terrestrial birds (Pantin-Jackwood & Swayne 2009;Slusher et al 2014;Shriner et al 2016) and wild mammals (Reperant et al 2009;Root et al 2015). Intermediate links such as farm workers' footwear may also be involved in virus transmission (Pepin et al 2014).…”